The Hair Growth Cycle
It should be explained that in most mammals, hair does not grow continuously, but undergoes a cycle of activity involving alternate periods of growth and rest. The hair growth cycle can be divided into three main stages, namely:
(i) the growth phase known as anagen, during which the hair follicle penetrates deep into the dermis with the cells of the bulb dividing rapidly and differentiating to form the hair, PA1 (ii) the transitional stage known as catagen, which is heralded by the cessation of mitosis, and during which the follicle regresses upwards through the dermis and hair growth ceases, PA1 (iii) the resting stage known as telogen, in which the regressed follicle contains a small secondary germ with an underlying ball of tightly packed dermal papilla cells. PA1 i) an effective amount of from 0.5 to 50% by weight of a glycosaminoglycanase inhibitor chosen from monosaccharide derivatives having the structure (1): ##STR1## where A.sup.1 and A.sup.6 are each chosen from ##STR2## B is OR" or a lactone linkage to position 1 or 6, or --NHCOCH.sub.3 and where PA1 R is --H or C.sub.1-20 alkyl, PA1 n is 0, or integer 1 or 2. PA1 ii) from 0.5 to 50% by weight of ethane diol; and PA1 iii) up to 99% by weight of a cosmetically acceptable vehicle for the glycosaminoglycanase inhibitor. PA1 i) Nicotinic acid and esters thereof, particularly benzyl, nicotinate, methyl nicotinate and ethyl nicotinate, PA1 ii) Panthenol PA1 iii) .alpha.-1,4 esterified disaccharides as described by Choay S.A. in EP-A-0 064 012, PA1 iv) Oligosaccharide deriviatives, as described by Unilever in EP-A-0 211 610, PA1 v) Minoxidil glucuronides, as described by Unilever in EP-A-0 242 967, PA1 vi) Minoxidil sulphates, as described by The Upjohn Co. in WO-A-86/04231, PA1 vii) Minoxidil, and other derivatives thereof as described by The Upjohn Co, in U.S. Pat. No. 4,139,619. PA1 viii) Proteoglycanase inhibitors, glycosaminoglycan chain cellular uptake inhibitors and glycosaminoglycanase inhibitor other than those disclosed herein, as described by Unilever in EP-A-0 277 428, PA1 ix) Ethylenediaminetetraacetic acid or salts thereof, as described by Redken Laboratories, Inc. in U.S. Pat. No. 4,814,351, PA1 x) Esters of pyroglutamic acid, as described by Lever Brothers Company in U.S. Pat. No. 4,774,255, especially: PA1 pyroglutamic acid n-hexyl ester, PA1 pyroglutamic acid n-octyl ester, PA1 ethyl-2-[pyroglutamoyloxy]-n-propionate, PA1 linoleyl-2-[pyroglutamoyloxy]-n-caprylate PA1 lauryl-2-[pyroglutamoyloxy]-n-caprylate PA1 stearyl-2-[pyroglutamoyloxy]-n-caprylate PA1 glyceryl mono(2-[pyroglutamoyloxy]-n-propionate) PA1 glyceryl mono(2-[pyroglutamoyloxy]-n-caprylate), PA1 and PA1 glyceryl di(2-[pyroglutamoyloxy]-n-propionate). PA1 xi) Aryl-substituted ethylenes, as described by Unilever in EP-A-0 403 238, PA1 xii) Mono N-acylated amino acids, as described by Unilever in EP-A-0 415 598, especially: PA1 N-acetyl glycine PA1 Xiii) Saturated or unsaturated aliphatic alcohols having an odd number of carbon atoms of from 3 to 25 in number, especially: PA1 n-nonyl alcohol PA1 xiv) Saturated or unsaturated aliphatic carboxylic acids having an odd number of carbon atoms of from 3 to 25 in number, especially: PA1 nonanoic acid PA1 xanthan gum PA1 guar gum PA1 locust bean gum PA1 Biopolymer PS 87 PA1 sodium carboxymethyl cellulose PA1 hydroxypropyl cellulose PA1 methyl cellulose PA1 carboxyvinyl polymer PA1 hectorites PA1 bentonites PA1 i) transdermal penetration, i.e. the amount retrieved in receptor fluid flowing on the dermal side of the skin; PA1 ii) tape strips, i.e. amounts of radio active material adhering to the skin surface; PA1 iii) upper section of skin, i.e. remainder of stratum corneum, neck of hair follicle, viable epidermis and upper part of dermis; PA1 iv) lower section of skin, i.e. remainder of dermis containing the remaining part of hair follicles and dermal papillae.
The initiation of a new anagen phase is revealed by rapid proliferation in the germ, expansion of the dermal papilla and elaboration of basement membrane components. The hair cycle is then repeated many times until, as a consequence of the onset of male pattern baldness, most of the hair follicles spend an increasing proportion of their time in the telogen stage, and the hairs produced become finer, shorter, and less visible; this is known as terminal to vellus transformation.
Also, as male pattern baldness proceeds, new hair growth, where it occurs, tends to be finer than before, this being due at least partly to a decrease in the average diameter of individual hair follicles. Although this phenomenon is seen as a very gradual development associated with ageing, it is most apparent when actual hair loss begins to occur, for example at the onset of male pattern baldness. At this stage, the decrease in the average diameter of individual hair follicles is more rapid.